[tracker/wip/carlosg/bus-statements: 4/6] libtracker-bus: Implement TrackerSparqlStatement

[Carlos Garnacho <carlosg src gnome org>]

commit 81508cb02eda42c20421069758cd25898f81f45b
Author: Carlos Garnacho <carlosg gnome org>
Date:   Sun Mar 1 15:43:39 2020 +0100

    libtracker-bus: Implement TrackerSparqlStatement
    
    Make it possible to create prepared statements on bus connections.
    
    Closes: https://gitlab.gnome.org/GNOME/tracker/issues/179

 src/libtracker-bus/meson.build                |  1 +
 src/libtracker-bus/tracker-bus-statement.vala | 93 +++++++++++++++++++++++++++
 src/libtracker-bus/tracker-bus.vala           |  4 ++
 3 files changed, 98 insertions(+)
---
diff --git a/src/libtracker-bus/meson.build b/src/libtracker-bus/meson.build
index 775afc73f..91fd74c34 100644
--- a/src/libtracker-bus/meson.build
+++ b/src/libtracker-bus/meson.build
@@ -2,6 +2,7 @@ libtracker_bus = static_library('tracker-bus',
     'tracker-bus.vala',
     'tracker-namespace.vala',
     'tracker-bus-fd-cursor.vala',
+    'tracker-bus-statement.vala',
     '../libtracker-common/libtracker-common.vapi',
     tracker_common_enum_header,
     c_args: tracker_c_args + [
diff --git a/src/libtracker-bus/tracker-bus-statement.vala b/src/libtracker-bus/tracker-bus-statement.vala
new file mode 100644
index 000000000..e5d78b933
--- /dev/null
+++ b/src/libtracker-bus/tracker-bus-statement.vala
@@ -0,0 +1,93 @@
+/*
+ * Copyright (C) 2020, Red Hat Ltd.
+ *
+ * This library is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU Lesser General Public
+ * License as published by the Free Software Foundation; either
+ * version 2.1 of the License, or (at your option) any later version.
+ *
+ * This library is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+ * Lesser General Public License for more details.
+ *
+ * You should have received a copy of the GNU Lesser General Public
+ * License along with this library; if not, write to the
+ * Free Software Foundation, Inc., 51 Franklin Street, Fifth Floor,
+ * Boston, MA  02110-1301, USA.
+ *
+ * Author: Carlos Garnacho <carlosg gnome org>
+ */
+
+public class Tracker.Bus.Statement : Tracker.Sparql.Statement {
+       private DBusConnection bus;
+       private string query;
+       private string dbus_name;
+       private string object_path;
+       private HashTable<string,GLib.Variant> arguments;
+
+       private const string ENDPOINT_IFACE = "org.freedesktop.Tracker1.Endpoint";
+
+       public Statement (DBusConnection bus, string dbus_name, string object_path, string query) {
+               Object ();
+               this.bus = bus;
+               this.dbus_name = dbus_name;
+               this.object_path = object_path;
+               this.query = query;
+               this.arguments = new HashTable<string, GLib.Variant> (str_hash, str_equal);
+       }
+
+       public override void bind_boolean (string name, bool value) {
+               this.arguments.insert (name, new GLib.Variant.boolean (value));
+       }
+
+       public override void bind_double (string name, double value) {
+               this.arguments.insert (name, new GLib.Variant.double (value));
+       }
+
+       public override void bind_int (string name, int64 value) {
+               this.arguments.insert (name, new GLib.Variant.int64 (value));
+       }
+
+       public override void bind_string (string name, string value) {
+               this.arguments.insert (name, new GLib.Variant.string (value));
+       }
+
+       public override void clear_bindings () {
+               this.arguments.remove_all ();
+       }
+
+       private VariantBuilder? get_arguments () {
+               if (this.arguments.size () == 0)
+                       return null;
+
+               VariantBuilder builder = new VariantBuilder (new VariantType ("a{sv}"));
+               HashTableIter<string, Variant> iter = HashTableIter<string, Variant> (this.arguments);
+               unowned string arg;
+               unowned GLib.Variant value;
+
+               while (iter.next (out arg, out value))
+                       builder.add ("{sv}", arg, value);
+
+               return builder;
+       }
+
+       public override Sparql.Cursor execute (GLib.Cancellable? cancellable) throws Sparql.Error, 
GLib.Error, GLib.IOError, GLib.DBusError {
+               // use separate main context for sync operation
+               var context = new MainContext ();
+               var loop = new MainLoop (context, false);
+               context.push_thread_default ();
+               AsyncResult async_res = null;
+               execute_async.begin (cancellable, (o, res) => {
+                       async_res = res;
+                       loop.quit ();
+               });
+               loop.run ();
+               context.pop_thread_default ();
+               return execute_async.end (async_res);
+       }
+
+       public async override Sparql.Cursor execute_async (GLib.Cancellable? cancellable) throws 
Sparql.Error, GLib.Error, GLib.IOError, GLib.DBusError {
+               return yield Tracker.Bus.Connection.perform_query_call (bus, dbus_name, object_path, query, 
get_arguments (), cancellable);
+       }
+}
diff --git a/src/libtracker-bus/tracker-bus.vala b/src/libtracker-bus/tracker-bus.vala
index 9b5453ecf..1a0d01db4 100644
--- a/src/libtracker-bus/tracker-bus.vala
+++ b/src/libtracker-bus/tracker-bus.vala
@@ -123,6 +123,10 @@ public class Tracker.Bus.Connection : Tracker.Sparql.Connection {
                return yield perform_query_call (bus, dbus_name, object_path, sparql, null, cancellable);
        }
 
+       public override Sparql.Statement? query_statement (string sparql, GLib.Cancellable? cancellable = 
null) throws Sparql.Error {
+               return new Bus.Statement (bus, dbus_name, object_path, sparql);
+       }
+
        void send_update (string method, UnixInputStream input, Cancellable? cancellable, AsyncReadyCallback? 
callback) throws GLib.Error, GLib.IOError {
                var message = new DBusMessage.method_call (dbus_name, object_path, ENDPOINT_IFACE, method);
                var fd_list = new UnixFDList ();